Variable speed transmission mechanism

ABSTRACT

A variable-speed transmission for use between two substantially parallel shafts for permitting continuous drive engagement during continuous speed-variation, and during power-variation of one shaft and corresponding change in operation of the other shaft.

111% Siates atent 1 1 [111 3,736,863 Horowitz et al. June 5, 1973 [54]VARIABLE SPEED TRANSMISSION 2,611,276 9 1952 Heynau ..74 192 H N M2,659,245 11/1953 McLaren.... ..74/690 2,676,492 4/1954 Frye et a1...74/192 Inventors: Alexandre Horowitz, Emhoven; 2,745,297 5/1956 Andrus..74/689 Bernard Joseph Beusink, Oerle; Martinus Hubertus Cuyper Bi d-FOREIGN PATENTS OR APPLICATIONS h Netherlands 688,974 3 1953 GreatBritain ..79/689 [73] Assignee: U.S. Philips Corporation, New

York, N.Y. Primary ExaminerArthur T. McKeon Filed: Mar 1971Att0rneyFrank R. Tr1far1 [21] Appl. No.: 128,045 [57] ABSTRACT [30]Foreign Application Priority Data A variable-speed transmission for usebetween two Mar. 26, 1970 Netherlands ..7004605 subsmntially Parallelshafts for Permitting continuous drive engagement during continuousspeed-variation, 52 us. 01. ..74/192, 74/689,74/690 and duringPower-variation of one Shaft and [51 t, 3 1 1, 15 42, 1 37 00 Flbh 37 0responding change in operation of the other shaft. [58] Field of Search..74/l92, 689, 690

[56] References Cited 8 Claims, 12 Drawing Figures UNITED STATES PATENTS2,233,967 3/1941 Wellton ..74/690 7 9 II 5 9 12 1a 1 PATENIEUJUH 5 I9753.738803 SHEET 1 [IF 8 Fig.1

I N VE NTORS ALEXANDRE HOROWITZ BERNARD JOSEPH BEUSINK BY MART INUS H.CUYPERS PATENTEUJUH 51975 SHEET 2 0F 8 IN VE N 'I'ORS ALEXANDRE HOROWITZBERNARD JOSEPH BEUSINK BY MARTINUS H. CUYPERS Age-n t PATENTEDJUN 5 I9753. 736.803

SHEET 3 BF 8 INVENTORS ALEXANDRE HOROWITZ BERNARD JOSEPH BEUSINK yMARTINUS H. CUYPERS mtmmm 5l975 3.736 303 sum u or 8 I Fig. 4

INVENTORS ALEXANDRE HOROWITZ BERNARD JOSEPH BEUSINK y MARTINUS u.CUYPERS Agent PATENTEDJUH 5 I973 SHEET 5 BF 8 Fig 5 Fig 7 INVENTORbALEXANDRE HOROW ITZ BERNARD JOSEPH BEUSINK BY MAR'IINUS n. CUYPERSPATENTEDJUM 5197s 3,736,803

SHEET 8 BF 8 Fig.9

INVENTORS ALEXANDRE HOROWITZ BERNARD JOSEPH BEUSINK y MARTINUS 1'1.CUYPERS PAIENTEUJUH 5:975 3.736.893

sum 7 OF 8 INVENTORS ALEXANDRE HOROWITZ BERNARD JOSEPH BEUSINK BYMARTINUS H. CUYPERS A ent PMENTEUJUN 5|975 3.736.803

sum a U? 8 INVENTORS ALEXANDRE HORQWITZ BY BERNARD JOSEPH BEUSINKMARTINUS H. CUYPERS Lowe/4%;

Agent VARIABLE SPEED TRANSMISSION MECHANISM The invention relates to avariable speed transmission mechanism between two substantially parallelshafts which each carry a guide wheel over which a friction ring passes.A pair of flanks of the ring engage a pair of flanks of at least one ofthe guide wheels, while a change in the spacing between the flanks of apair of flanks causes a change in the position of the ring relative tothe guide wheel and hence in the transmission ratio.

The shafts to be coupled carry split guide wheels the two parts of whichare axially displaceable against spring force. The friction ring ismounted for rotation in a frame which is displaceable by means of anoperating mechanism.

Similar transmission mechanisms are known which are fitted with anoperating mechanism which enables the spacing between the parts of theguide wheels and hence the position of the ring and consequently thetransmission ratio to be varied.

A disadvantage of these known variable-speed transmission mechanisms isthe complicated and hence expensive and vulnerable construction of themechanism for varying the transmission ratio. Moreover, the forcesexerted on the ring by the moment to be transmitted from one shaft tothe other frequently have to be absorbed entirely or largely by the saidmechanism so that the mechanism must be of heavy construction and bulky.

It is an object of the invention to avoid the said disadvantages, andthe construction according to the invention is characterized in that inorder to vary the position of the ring relative to one of the guidewheels, the ring is adapted to be tilted about the other guide wheel.

The variation of the transmission ratio may be adjustable at will bymeans of a construction which is characterized in that the friction ringis also passed around an adjusting wheel which is displaceable by meansof an operating mechanism.

The transmission mechanism may be made selfadjusting in an embodimentwhich is characterized in that the friction ring is exclusivelysupported by the guide wheels on the two shafts and is automaticallyadjustable by forces exerted on it by the guide wheel flanks.

A preferred embodiment is characterized in that the guide wheel aboutwhich the ring is pivotable takes the form of an externally toothedgearwheel, the friction ring being provided with corresponding internalteeth.

A particular embodiment is characterized in that the friction ring iscomposed of two annular elements which together form an annular unit andare resiliently joined together.

The annular element may be joined together either by resilient elementswhich are uniformly distributed around the circumference or by a rimmade of a resilient material.

A construction which is continuously adjustable within very wide limitsis characterized in that the transmission mechanism is combined with adifferential gear, the motion of the input shaft being divided into twomotions, namely that of the output shaft and that of a third shaft,which motions are in a variable ratio to one another, the third shaftbeing coupled to one of the two other shafts by the variabletransmission mechamsm.

Such a combination with a differential gear may in particular take aform which is characterized in that the differential mechanism comprisesan epicyclic gearing with a sun gear on the input shaft and at least oneplanet gear coupled to the output shaft, the annulus having externalteeth which mesh with a gearwheel on the third shaft, the guide wheelsof the variable transmission mechanism being mounted on the third shaftand on the shaft coupled to the third shaft respectively, while thefriction ring passing over the guide wheels occupies a position whichdetermines the transmission ratio and which is variable undertheinfluence of the moment to be transmitted by the third shaft.

Embodiments of the invention will now be described, by way of example,with reference to the accompanying diagrammatic drawings:

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an axial sectional view of avariable transmission mechanism,

FIG. 2 is a sectional view taken at right angles to the shaft on theline IIII of FIG. 1,

FIG. 3 shows schematically the friction ring of FIG. 1 in two positions,

FIG. 4 is a sectional view of a variable transmission mechanismincluding a separate adjusting wheel, taken at right angles to theshafts,

FIG. 5 is a sectional view of part of a specific embodiment of a splitguide wheel and a fitting friction ring,

FIG. 6 is a sectional view in a plane containing the shafts of avariable transmission mechanism having a friction ring composed of twoannular elements which are resiliently joined together,

FIGS. 7 and 8 are sectional views of modifications of the guide wheeland the friction ring,

FIG. 9 is a sectional view taken in a plane containing the shafts of atransmission mechanism according to the invention in which an epicyclicgearing is combined with a variable-speed transmission mechanism havinga self-adjusting friction ring passing over guide wheels,

FIG. 10 is a sectional view taken on the line X-X of FIG. 9,

FIG. llis a schematic perspective view of the transmission mechanism ofFIG. 9,

FIG. 12 is a graph in which the relationship between the moment appliedto the output shaft and the ratio between the peripheral velocities ofthe input and output shafts is plotted.

OF THE PREFERRED EMBODIMENT Referring now to FIGS. 1 and 2, guide wheels1 and 2 are mounted on shafts 3 and 4 respectively to be coupled. Ametal friction ring 5 passes over the guide wheels 1 and 2. The ring 5has internal teeth which mesh with corresponding external teeth of theguide wheel 2. The guide wheel 1 is composed of two parts 7 and 8between which the ring 5 is disposed. The radial distance of the shaft 3from the points of contact 9 between the ring 5 and each of the parts 7and 8 determines the transmission ratio in transmitting the rotationmovement from the shaft 3 to the shaft 4 and vice versa. The part 8 ofthe guide wheel 1 is integral with the shaft 3. A shaft 10 is alignedwith the shaft 3. The shafts 3 and 10 are interconnected by a bolt 11 soas to be axially adjustable. A spring abutment 12 is rigidly secured tothe shaft 10. Cup-shaped spring elements 13 are tensioned between thespring abutment l2 and the part 7 of the guide wheel 1. As a result, thepart 7 is adapted to slide axially on the shaft 3, so that the positionof the ring relative to the two parts 7 and 80f the guide wheel 1 andhence the locations of the contact points 9 which determine thetransmission ratio are variable. This change in position of the ringrelative to the split guide wheel 1 may be considered as a pivotingmovement of the ring about the guide wheel 2. During the pivotingmovement the center M of the ring 5 moves along the arc of a circlehaving its center in the axis of the shaft. As will be described morefully hereinafter with reference to FIG. 3, the transmission mechanismmay be designed so that this change in position is automaticallyeffected under the influence of the forces exerted on the ring by theguide wheels.

FIG. 3 shows schematically the ring 5 in two positions relative to theguide wheels 1 and 2 and also the forces exerted by the guide wheel 1 onthe ring 5. One of these two positions is shown by a broken line and thereference characters relating to this position are distinguished by aprime. Assuming the shaft 3 which carries the guide wheel 1 to be thedriving shaft and the direction of rotation to be as indicated by thearrows, in the first position of the ring 5, in which position thecenter of the ring is at M, the guide wheel 1 exerts a tangential forceK, and a radial force K, on the ring 5 in the contact point 9. In thestationary condition the moment of the resultant of the forces K, and K,about a theoretical point 14 of contact between the ring 5 and the guidewheel 2 is zero, i.e. K,.A is K,.b. If the force K, increases, forexample because the resisting torque applied to the driven shaft 4 isincreased, the moment K,.a will become greater than K,.b and the ringwill move to a new equilibrium position, for example the position inwhich the center is located at M. Thus, the contact point 9 has beenmoved to 9' at a smaller radial distance from the shaft 3. The two parts7 and 8 of the guide wheel 1, which in a cross-sectional view enclose agroove which tapers towards the shaft, are thrust apart against theaction of spring elements 13 (cf. FIG. 1 also). A new position ofequilibrium is reached because with respect to the new contact point 14of the ring 5' and the guide wheel 2 the moment arm a of the force K, issmaller than the moment arm a for the force K while the moment arm b ofthe force K, has increased with respect to the moment arm b of the forcel(,.. Moreover, in general the force K, will change on movement of thering 5 relative to the parts 7 and 8, and in the embodiment shown inFIG. I, K, will be greater than I(,. However, the connection between thepart 7 and 8 by means of spring elements may be differently designed,for example in a manner such that the force which these spring elementsexert on one another is constant, irrespective of the relative positionsof the parts 7 and 8.

Thus a self-adjusting transmission mechanism is obtained which onincrease of the resisting torque applied to the driven shaft 4, willautomatically adjust itself to a lower speed for this shaft.Consequently, an increase in the power to be transmitted iscounteracted, which is also due to the fact that the greater force K,has a smaller moment arm with respect to the shaft 3 than has the forceI(,. Conversely, a decrease in the power In addition to the above effecttending to automatically maintain constant the speed of the drivingshaft, the transmission mechanism may also be used for maintainingconstant the speed of the driven shaft, In this case the shaft 4carrying the guide wheel 2 is the driving shaft and the directions ofrotation of the guide wheels 1 and 2 are opposite to the directions ofthe arrows. An increase in the force K,, for example due to an increaseof the resisting torque of the shaft 3, again causes a displacement ofthe contact point 9 to 9', which in general will be accompanied by adecrease in the speed of the shaft 4. A corresponding decrease in thespeed of the shaft 3 is counteracted, because the contact point 9 isspaced from the shaft 3 by a smaller radial distance than is the contactpoint 9.

The guide wheel 2 need not be in the form of gearwheel, but it mayalternatively be a roller or pulley having a groove for the ring formedin it, the movement being transmitted from the ring 5 to the guide wheel2 and vice versa by means of frictional forces. The only condition isthat the ring is adapted to pivot about this guide wheel 2.

Alternatively, both guide wheels 1 and 2 may be split in the mannerdescribed hereinbefore with respect to the guide wheel 1. When the guidewheels 1 and 2 are identically shaped, changing conditions willtheoretically cause the ring to change its position relative to the twoguide wheels in the same sense and in the same degree, so that thetransmission ratio remains unchanged. If, however, the two guide wheels1 and 2 differ from one another, for example, in the slopes of thefriction flanks or in the properties of the springs by which the guidewheel parts are coupled to one another, in general automatic adjustmentof the transmission ratio by the ring will nevertheless be possible. Inthis case the change in position of the ring may be described as acombination of a translation and a rotation about one of the guidewheels.

The self-adjusting transmission mechanism described with reference toFIGS. 1 to 3 is distinguished by its simple construction. There is noneed for special mechanisms for displacing the ring, for intercouplingthe guide wheels or guide wheel parts or for displacing one or bothshafts. Hence, the afore-described variable transmission mechanism maybe built in a highly compact form.

FIG. 4 shows an embodiment in which the ring automatically adjustsitself but in which the position of the ring may also be determined bymeans of a roller 23 over which the ring runs and which may be displacedfrom the exterior. The roller 23 is mounted on an arm 24 of a bell-crank25 which is pivotable about a pivot 26. The position of the roller 23 isadjustable by means of a Bowden cable 27, which passes through a casing28 and is secured to the end of the other arm 29 of the bell-crank 2 5.The roller 23 may alternatively be disposed so as to engage the outersurface instead of the inner surface of the ring 5. If the inner surfaceof the ring 5 carries teeth, the roller 23 may be replaced by agearwheel. Another alternative is for the roller 23 to run in acircumferential groove traversing the teeth. If the limb 24 carries anadditional roller disposed opposite the rdller 23 and engaging the outersurface of the ring 5, the position of the ring 5 and hence thetransmission ratio between the shafts 3 and 4 is completely determinedby the position of the bell crank 25. The position of the bell crank maybe manually adjusted.

FIG. 5 shows an embodiment using a friction ring of U-shapedcross-section. Flanks 16 and 17 at the inner surface of the limbs ofthis ring 15 engage flanks 18 and 19 of the parts 20 and 21 of a guidewheel. The guide-wheel parts 20 and 21 are joined together by springelements 22 and are axially movable relative to one another, so that theposition of the annular trans mission member 15 is again variable. Aring 15 having a cross-section as shown in FIG. 5 may, for example, beused in a variable transmission mechanism of the aforedescribed type.The guide wheel composed of parts 20, 21 and 22 will then be substitutedfor the guide wheel 1 of FIGS. 1 to 4.

If large powers are to be transmitted, several pairs of guide wheels 1and 2 may be mounted on the shafts 3 and 4 respectively, a ring 5 or 15running over each pair. The self-adjusting transmission mechanism shownin FIGS. 1 to 3 is particularly suited for such a parallel arrangement.In such an arrangement the rings 5 or 15 will automatically adjustthemselves to the same transmission ratio because, if a ring tends todepart from it, forces will act on this ring which will immediatelycorrect the deviation in the afore-described manner.

FIG. 6 is a cross-sectional view of an embodiment taken in a planecontaining the shafts, which embodiment includes a friction ringconsisting of two annular elements 30 and 31 joined together by springelements 32. In this embodiment, a guide wheel 33 on the shaft 3 needsnot comprise two relatively displaceable parts and has a groove formedin it which tapers towards the center of the wheel 33. The shaft 4carries a guide wheel 34 in which likewise a groove for the frictionring has been formed. The transmission of motion between the guidewheels and the ring is effected by means of the frictional forcesbetween the flanks of the ring and the walls of the grooves in the guidewheels. Moreover, the inner surfaces of the annular elements 30 and 31are in contact with the bottom 35 of the groove in the guide wheel 34and this contact also will produce frictional forces. Hence the groovedguide wheel 34 on the shaft 4 may be replaced by a friction roller.

Also, the annular elements 30 and 31 may be provided with internal teethwhich mesh with a gearwheel on the shaft 4.

The annular elements 30 and 31 are adapted to tilt about the guide wheel34, so that in complete correspondence with the principle of theembodiments described with reference to FIGS. 1 to 4 the transmissionratio is variable.

FIG. 7 shows an embodiment in which the friction ring likewise iscomposed of two annular elements 36 and 37 which again are joinedtogether by spring elements 38. These spring elements 38 exert forcesdirected towards each other on the elements 36 and 37,

I so that these elements are clamped onto sloping flanks 39 and 40 of aguide wheel 41 on the shaft 3. FIG. 8 shows a modification of the ringof FIG. 7. In this modified ring, the two annular elements 42 and 43 arejoined together by a resilient ring 44. The elements 42 and 43 and thering 44 form an integral unit made of a material having elasticproperties, for example, a synthetic material. The elements 42 and 43are reinforced by metal cores 45 and 46 respectively. A variabletransmission mechanism according to the principle described withreference to FIGS. 1 to 4 may again be readily realized by means of theembodiments shown in FIGS. 7 and 8.

A particularly compact transmission mechanism the transmission ratio ofwhich is variable within very wide limits is obtainable by combining avariable transmission mechanism of the aforedescribed type with adifferential gear. Such a combination is shown in FIGS. 9 to l l.

The transmission mechanism includes a epicyclic gearing whichintercouples shafts 47, 48 and 49. The input shaft 47 is driven, forexample by an electric motor 50, and its other end carries a sun gear 51of the epicyclic gearing. A planet gear 52 of the gearing meshes withthe sun wheel 51. The planet gear 52 is mounted for rotation about aspindle 53 one end of which is secured in an end part 54 of the outputshaft 48, which end part 54 has a greater diameter than the remainder ofthe shaft 48. An annulus 55 of the epicyclic gearing has internal teethand external teeth which mesh with the planet gear 52 and with a thirdgear wheel 56 on the third shaft 49 respectively. The epicyclic gearingfurther has three supporting gearwheels 57 each mounted for rotationabout a corresponding spindle 58. One end of each spindle 58 is rigidlysecured in the end part 54 of the output shaft 48.

The shafts 47 and 49 are also coupled to one another by a metal frictionring 59 which passes over two guide wheels 60 and 61. The guide wheel 60is rigidly mounted on the shaft 47 and has the form of a gearwheelmeshing with internal teeth of the ring 59. The guide wheel 61 is splitand the two parts 62 and 63 are axially displaceable with respect to oneanother in the manner described with reference to the embodiments shownin FIGS. 1 to 4.

The output shaft 48 carries a gearwheel 64 for driving a tool. Inresponse to the resisting torque acting on the shaft 48 the transmissionmechanism will automatically adjust itself. If the variable-speedmechanism is set to a given transmission ratio, the ratio between thespeeds of the shafts 47, 48 and 49 is uniquely determined. In thestationary condition, the ratio between the moments to be transmitted bythe shafts 47, 48 and 49 is also uniquely determined by the dimensionsof the sun gear 51, the planet gear 52, the annulus 55 and the gearwheel56. If the moment to be transmitted by the shaft 48 changes, for examplebecause the driven tool requires another moment, the moment to betransmitted by the shaft 49 will be proportionately changed. The changein the moment acting on the shaft 49 is used for automatic adjustment ofthe position of the ring 59 between the parts 62 and 63 of the guidewheel 61 and hence of the transmission ratio in the aforedescribedmanner. FIG. 11 shows the ring in two positions which correspond todifferent transmission ratios, the ring in the position shown by brokenlines being designated by 59'. The location of the variable speedtransmission mechanism which automatically responds to the moment to betransmitted is variable. Instead of being interposed between the shafts47 and 49 it may be used to couple the shafts 48 and 49. This permits ofobtaining transmission mechanisms having different properties, which maybe adapted to the requirements to be satisfied by the tool to be driven.In the graph shown in FIG. 12, a curve I shows the relationship betweenthe moment M acting on the output shaft 48 and the transmission ratiobetween the input shaft 47 and the output shaft 48 in the embodimentdescribed with reference to FIGS. 9 to 11. The transmission ratio isdefined as a) m where m. and m are the angular velocities of the inputand output shafts 47 and 48 respectively. The curve I shows that afinite moment acting on the output shaft is maintained even if the speedof the output shaft is zero. This property may advantageously be usedfor driving different devices such as mixers, mills, drills, lawnmowers, boats, motor cars, motor bicycles and the like. If the outgoingshaft meets an obstruction such that its speed becomes zero, the inputshaft and the power source coupled to it will remain re-. volving,whilst a finite torque keeps acting on the output shaft. This preventsthe transmission mechanism from breaking itself up in the case of theoutput shaft being obstructed. Since at zero speed of the outgoing shaftthis shaft does not transmit power, the input shaft need not supplypower apart from the losses produced in the transmission mechanismitself. The mechanism contains a so-called circulating power which iscirculated via the input shaft 47, the differential gearing the thirdshaft 49 and the variable-speed transmission mechanism.

If in the embodiment described with reference to FIGS. 9 to l 1, thedrive is coupled to the third shaft 49, which as a result actuallybecomes the input shaft whilst the former input shaft takes the place ofthe third shaft, the curve II of FIG. 12 is obtained. This curveshows aninitial increase of the transmission ratio with increase of the momentacting on the output shaft, whilst beyond a given value the transmissionratio continues to increase with decrease of the said moment.

What is claimed is:

l. A transmission mechanism for continuous and variable speed changebetween first and second shafts which are in substantially parallelfixed relative positions, comprising a first guide wheel keyed to saidfirst shaft, a friction ring substantially in said plane and encirclingthe first wheel, with an inner edge of the ring in drive engagement withan adjacent outer edge of said wheel, a second guide wheel comprisingtwo disc parts axially spaced apart, at least one disc spring-biasedtoward the other, the discs rotatable on said second shaft with at leastone disc keyed to said second shaft, said ring having a portion thereofsituated between and in frictional engagement with said two discs, saidring being pivotable about said first wheel with an edge of the ringalways in contact with said first wheel, and a second portion of thering engaging said discs along varying radially spaced parts thereof,said ring automatically varying its radial position relative to saidsecond wheel according to the forces exerted on said ring by said wheel,with a resulting change in the speed ratio between said first and secondshafts.

2. A variable-speed transmission mechanism as claimed in claim 1 furthercomprising an adjusting wheel rotatably mounted in said frame, said ringcircumscribes the adjusting wheel, the mechanism further comprisingmeans for displacing said adjusting wheel to pivot said ring to adifferent position.

3. A variable'speed transmission mechanism as claimed in claim 1characterized in that the first guide wheel about which the ring pivotscomprises an externally toothed gearwheel, and the friction ring hascorresponding internal teeth.

4. A variable-speed transmission mechanism as claimed in claim 1 whereinthe second wheel further comprises spring elements uniformly distributedaround the circumferences of said discs.

5. A variable-speed transmission mechanism as claimed in claim 1 whereinthe second wheel further comprises a rim made of a resilient materialfor biasing together said discs.

6. A transmission mechanism for continuous, variable speed changebetween first and second shafts, which are mounted in substantiallyparallel, fixed relative positions in a frame, comprising: first andsecond wheels respectively keyed to said shafts, a friction ringcircumscribing the first wheel in constant driving engagement therewith,and frictionally engaging the second wheel at positions spaced atvariable radial distances from the axis of said second wheel, the radialposition of said ring relative to said second wheel being automaticallyvaried as compensation for variation of the forces exerted by the secondwheel on said ring.

7. A variable-speed transmission mechanism between two substantiallyparallel shafts rotatably mounted in a frame, comprising: first andsecond wheels keyed to said first and second shafts respectively, thetwo wheels in a plane that is generally normal to said axes of saidshafts and wheels, the first wheel having a circumferential contactedge, the second wheel having a friction surface generally in saidplane, and a friction ring that circumscribes the first wheel in driveengagement with said contact edge, and contacts the second wheel infrictional engagement with said friction surface, a moment-arm distancebeing established from the two points of engagement of said ring withsaid two wheels,

said ring being pivotable about said first wheel such that a remote partof the ring contacts said second wheelss frictional surface at avariable radial distance from its axis with the frictional forces fromsaid contact being operative on the resulting moment-arm distance to thepivot point on said first wheel, said frictional contact point andcorresponding forces being automatically variable with a change in speedor load between said shafts.

8. A variable-speed transmission mechanism as claimed in claim 1characterized in that the first wheel about which the ring pivotscomprises an externally toothed gearwheel, and the friction ring hascorresponding internal teeth.

mg UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No.3,736,803 Dated June 7 ALEXANDRE HOROWITZ ET' AL It 1e certified thaterror appears in the above-identified patent and that said LettersPatent are hereby corrected as shown below:

In the heading [30] Foreign Application Priority Data" "Mar. 26, 1970"should be April l, 1970-- Signed and sealed this 9th day of April19714..

(SEAL) Attest:

C MARSHALL DANN Commissioner of Patents EDl/JARD I LFLETCHER,JR. Attesting Officer

1. A transmission mechanism for continuous and variable speed change between first and second shafts which are in substantially parallel fixed relative positions, comprising a first guide wheel keyed to said first shaft, a friction ring substantially in said plane and encircling the first wheel, with an inner edge of the ring in drive engagement with an adjacent outer edge of said wheel, a second guide wheel comprising two disc parts axially spaced apart, at least one disc spring-biased toward the other, the discs rotatable on said second shaft with at least one disc keyed to said second shaft, said ring having a portion thereof situated between and in frictional engagement with said two discs, said ring being pivotable about said first wheel with an edge of the ring always in contact with said first wheel, and a second portion of the ring engaging said discs along varying radially spaced parts thereof, said ring automatically varying its radial position relative to said second wheel according to the forces exerted on said ring by said wheel, with a resulting change in the speed ratio between said first and second shafts.
 2. A variable-speed transmission mechanism as claimed in claim 1 further comprising an adjusting wheel rotatably mounted in said frame, said ring circumscribes the adjusting wheel, the mechanism further comprising means for displacing said adjusting wheel to pivot said ring to a different position.
 3. A variable-speed transmission mechanism as claimed in claim 1 characterized in that the first guide wheel about which the ring pivots comprises an externally toothed gearwheel, and the friction ring has corresponding internal teeth.
 4. A variable-speed transmission mechanism as claimed in claim 1 wherein the second wheel further comprises spring elements uniformly distributed around the circumferences of said discs.
 5. A variable-speed transmission mechanism as claimed in claim 1 wherein the second wheel further comprises a rim made of a resilient material for biasing together said discs.
 6. A transmission mechanism for continuous, variable speed change between first and second shafts, which are mounted in substantially parallel, fixed relative positions in a frame, comprising: first and second wheels respectively keyed to said shafts, a friction ring circumscribing the first wheel in constant driving engagement therewith, and frictionally engaging the second wheel at positions spaced at variable radial distances from the axis of said second wheel, the radial position of said ring relative to said second wheel being automatically varied as compensation for variation of the forces exerted by the second wheel on said ring.
 7. A variable-speed transmission mechanism between two substantially parallel shafts rotatably mounted in a frame, comprising: first and second wheels keyed to said first and second shafts respectively, the two wheels in a plane that is generally normal to said axes of said shafts and wheels, the first wheel having a circumferential contact edge, the second wheel having a friction surface generally in said plane, and a friction ring that circumscribes the first wheel in drive engagement with said contact edge, and contacts the second wheel in frictional engagement with said friction surface, a moment-arm distance being established from the two points of engagement of said ring with said two wheels, said ring being pivotable about said first wheel such that a remote part of the ring contacts said second wheels''s frictional surface at a variable radial distance from its axis with the frictional forces from said contact being operative on the resulting moment-arm distance to the pivot point on said first wheel, said frictional contact point and corresponding forces being automatically variable with a change in speed or load between said shafts.
 8. A variable-speed transmission mechanism as claimed in claim 1 characterized in that the first wheel about which the ring pivots comprises an externally toothed gearwheel, and the friction ring has corresponding internal teeth. 